The invention relates to a bogie construction particularly intended for specially heavy vehicles, such as mining vehicles, the bogie construction comprising at least two interconnected stiff axles, which form a bogie, at least some of the axles belonging to the bogie being turnable when the vehicle is steered with respect to a vertical pivoted axle mounted between the ends of the axles which are steerable with respect to the frame of the vehicle, and for interconnecting the axles belonging to the bogie. The bogie construction is provided with a rocking lever, which is arranged to turn with respect to the transverse axle of the vehicle between its ends and move in the longitudinal direction of the vehicle as a result of a steering movement of the axles in the bogie.
Stiff axles are commonly used in vehicles intended for especially heavy transports, such as heavy transport equipment, machinery, mining vehicles and the like. It is preferable to provide such vehicles with stiff axles because the loads are heavy. A structure of this kind is also simpler and thus more durable. Furthermore, the use of stiff axles is economically feasible. Usually there are more than two axles per vehicle in heavy vehicles, and axles are combined into bogie constructions using different levers and springs, which allows distribution of the load between several axles. In the case of axle constructions of specially heavy vehicles one also needs to consider the effect of the load carried by the vehicle, which may be arranged rather unevenly, and the effect of an uneven support (road) surface. Furthermore, since heavy vehicles typically also have large outer dimensions, i.e., they are long and wide, one usually needs to be able to steer more than one axle to be able to manage them easier. The turning radius can be reduced substantially if all axles are arranged to turn when the vehicle is steered.
Stiff axles which are turned during steering are typically combined with each other into a bogie construction using an equalizer lever or the like, usually by means of a rocking lever pivoted between its ends. Important design considerations include the fact that the wheels on the different sides of the vehicle move along turning circles with different radii when the vehicle is steered, and the additional fact that successive axles need to be able to turn by a different angle depending on their location in the longitudinal direction of the vehicle so that successive wheels could move along the same turning circle. In one prior art arrangement, the rocking lever interconnecting the axles is arranged to move in the longitudinal direction of the vehicle by pivoting it on a turning axle and by connecting it to other axles by various suspension rods and joints. There are also prior art proposals where the rocking lever is pivoted on the frame, and thus there are pivoted suspension rods mounted between the axles and the rocking lever, which allow the axles to move as required for steering. A disadvantage associated with the prior art structures is that a lot of space is required for the structure so that the levers can turn in the manner required for steering. A further problem is that steering causes the vehicle frame to move in the up and down direction, which requires considerable steering forces. Because the steering members have to lift the mass of the vehicle and the load carried by it when the vehicle turns, wheel suspension and steering members are loaded considerably.
An object of the present invention is to provide a new bogie construction for especially heavy vehicles, such as mining vehicles, which eliminates problems of the prior art.